75th Annual Meeting of the APS Division of Fluid Dynamics (November 20, 2022 — November 22, 2022)

V0056: A droplet devouring its jet

Authors

• Uddalok Sen, Physics of Fluids Group, Max Planck Center Twente for Complex Fluid Dynamics, Department of Science and Technology, and J. M. Burgers Centre for Fluid Dynamics, University of Twente, The Netherlands
• Detlef Lohse, Physics of Fluids Group, Max Planck Center Twente for Complex Fluid Dynamics, Department of Science and Technology, and J. M. Burgers Centre for Fluid Dynamics, University of Twente, The Netherlands
• Javier Rodríguez Rodríguez, Fluid Mechanics Group, Carlos III University of Madrid, Spain

DOI: https://doi.org/10.1103/APS.DFD.2022.GFM.V0056

When a drop with a complex composition --such as those exhaled in respiratory activities-- evaporates in an acoustic levitator, its properties change over time as the most volatile component (water) evaporates. This leads to a reduction in the drop's surface tension which, in turn, causes the drop to flatten as a result of the push of the same acoustic pressure forces that keep it levitated. And then, when the flatteing exceeds a critical value ... topological transition happens! In a matter of milliseconds, the flattened drop buckles to turn into a "soap bubble" which remains stable for several minutes. This topological transition is a rather violent process which generates two powerful Worthington jets : one that escapes downwwards, and another one that is devoured by the drop-turned-into-bubble to result into a tiny encapsulated drop. A Fluid Mechanics allegory of the mythological picture of a Titan devouring his son.